How do I run Asynchronous callbacks in Playground

Question

Many Cocoa and CocoaTouch methods have completion callbacks implemented as blocks in Objective-C and Closures in Swift. However, when trying these out in Playground, the co

Answer 1

As of XCode 7.1, XCPSetExecutionShouldContinueIndefinitely() is deprecated. The correct way to do this now is to first request indefinite execution as a property of the current page:

import XCPlayground

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

…then indicate when execution has finished with:

XCPlaygroundPage.currentPage.finishExecution()

For example:

import Foundation
import XCPlayground

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

NSURLSession.sharedSession().dataTaskWithURL(NSURL(string: "http://stackoverflow.com")!) {
    result in
    print("Got result: \(result)")
    XCPlaygroundPage.currentPage.finishExecution()
}.resume()